Actually, that one's quite easy.
Women who are messed up are vulnerable. And men find vulnerable women irresistable. It appeals to the Sir Lancelot Gene.
Back when I was living much more poorly, I had the occasion to be around women that could only be described as crack ho's. To a woman, no matter how hideous she appeared, they'd have very nice and normal men pursuing them. I talked with one such woman one time, and she broke it down: I'm vulnerable because I'm an addict, and men want to rescue me.
It appeals to the Sir Lancelot Gene.
Wrong, it appeals to the guy who wants to seal some kind of deal where the woman will remain loyal. It's the male equiv. of women sealing the deal with sex.
Obviously "the deal" inevitably falls apart and the injured party gets to hear "But...but...but...I...but...I...I can't believe....but....but.." run through their head for an extended period of time.